How to export an animation with timeScale and weight applied as a new animation in three.js?

My ideia is an application where I can edit animation applying timeScale, weight or other things and export as a new animation to glTf or other format.

In general glTF does only define how animation data are stored. Runtime related playback behavior like time scaling is not supported. Hence, you have to modify the animation’s time values so GLTFExporter is able to produce a desired glTF file.